2个 相关联的配置文件分别为：
Tuser.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC    
  "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.randy.connection">
  <class name="Tuser" table="t_user">
    <id name="id">
    <generator class="foreign">
      <param name="property">passport</param>
    </generator>
    </id>
    <property name="age" />
    <property name="name"/>
    
    <one-to-one name="passport" cascade="all" class="Tpassport" constrained="true"/>
  </class>
    
    
</hibernate-mapping>
 
Tpassport.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC    
  "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.randy.connection">
  <class name="Tpassport" table="t_passport">
    <id name="id">
      <generator class="native" />
    </id>

    <property name="serial" />
    
  </class>
    
    
</hibernate-mapping>
执行的代码
  public void testSelect(){
    String hql ="from Item";
    List userlist = session.createQuery(hql).list();
  }
 
输出的sql
 select tuser0_.id   as id0_0_,
        tuser0_.age  as age0_0_,
        tuser0_.name as name0_0_
   from t_user tuser0_
  where tuser0_.id = ?
----------------------------------------
 select tpassport0_.id as id1_0_, tpassport0_.serial as serial1_0_
   from t_passport tpassport0_
  where tpassport0_.id = ?
 
 
共2条SQL 语句
 
实验：
当把 Tuser.hbm.xml文件中<one-to-one>标签中的contained="true"去掉了
输出的sql:
 select tuser0_.id         as id0_1_,
        tuser0_.age        as age0_1_,
        tuser0_.name       as name0_1_,
        tpassport1_.id     as id1_0_,
        tpassport1_.serial as serial1_0_
   from t_user tuser0_
   left outer join t_passport tpassport1_ on tuser0_.id = tpassport1_.id
  where tuser0_.id = ?
 
一条sql语句。
 
测试代码：
  public void testDelete(){
    Transaction tc = null;
    try{        
      tc = session.beginTransaction();
      Tuser user =(Tuser)session.load(Tuser.class, 5);
      //Tuser user = new Tuser();
    //  user.setId(3);
      session.delete(user);
        
      tc.commit();
    }catch(HibernateException e){
      tc.rollback();
      e.printStackTrace();
    }
  }
 
这里的load() 可以替换为get()
1.当Tuser.hbm.xml 中one-to-one 标签中的casecade="true"的时候
输出 2条sql
delete from t_user where id=?
delete from t_passport where id=?
 
2.当Tuser.hbm.xml 中one-to-one 标签中的casecade="false"的时候
只输出一条sql
delete from t_user where id=?
 
测试代码：
  public void testDelete(){
    Transaction tc = null;
    try{        
      tc = session.beginTransaction();
      Tuser user = new Tuser();
      user.setId(3);
      session.delete(user);
        
      tc.commit();
    }catch(HibernateException e){
      tc.rollback();
      e.printStackTrace();
    }
  }
 
 
1.当Tuser.hbm.xml 中one-to-one 标签中的casecade="false"的时候
 
输出一条sql
delete from t_user where id=?
2.当Tuser.hbm.xml 中one-to-one 标签中的casecade="false"的时候
delete from t_user where id=?
 
太奇怪了，失效了casecade 属性没用了。